Constantin G. Economou Memorial Lecture

A core feature of many living systems is their ability to move, to self-propel, to be active.  Through their self-motion living systems of all scales display collective behavior; bacteria swarms, fish schools, bird flocks, buffalo herds, etc.  Unlike non-living, passive systems that are in thermal equilibrium with their surroundings, active matter is a nonequilibrium system that is not constrained by conventional thermodynamic laws.  In this work we discover a unique "swim pressure" exerted by active matter systems and use this new perspective to identify what may be the basic underlying physical mechanism responsible for self-assembly and pattern formation in all active matter.  Our new swim pressure perspective may help enable the design and control of active systems, from swimming bacteria and catalytic nanobots to molecular motors that activate the cellular cytoskeleton.